watch_item_t: pass entity_addr_t by reference

CID 1030127 (#1 of 1): Big parameter passed by value (PASS_BY_VALUE)
 pass_by_value: Passing parameter addr of type entity_addr_t (size 136
 bytes) by value.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>